Abstract
Rapid urbanisation throughout the world has resulted in numerous ecological and environmental problems. The release of contaminants into the aquatic environment and the subsequent accumulation in sediment is a specific area of concern due to the potential re-release of the contaminants into solution. The responses of two microbiotests designed to evaluate sediment toxicity (the Ostracodtoxkit F and Phytotoxkit test) were compared once exposed to three samples collected in the vicinity of a power station in Mpumalanga, South Africa. Sediment characterisation and chemical analyses were conducted in order to determine possible correlations with the expressed results. Where possible, the concentration of chemicals in the sediment was compared to available sediment guidelines. The study showed that whilst the Phytotoxkit test results did not indicate any acute toxicity (< 50% inhibition), the Ostracodtoxkit F test indicated 100% mortality at the upstream site, with increased growth inhibition at the remaining two sites. The concentration of chrome at all three sites exceeded the interim sediment quality guidelines (37 mg/kg), with the sample collected at the upstream site exceeding the probable effect level (90 mg/kg). The findings from this study indicated that the Phytotoxkit and Ostracodtoxkit F test kits are sensitive enough to evaluate sediment toxicity. Keywords: Ostracodtoxkit F, Phytotoxkit, sediment contamination
Highlights
Metals (e.g. V, Cd, Pb and N) and nutrients (P, N and NH4+) can enter the aquatic environment (Dallas and Day, 2004) through naturally occurring events as well as anthropogenic activities
Results from the grain size analysis (Fig. 1) for the upstream site indicated that the sediment mainly consisted of very fine sand (31%), medium sand (34%) and coarse sand (29%)
Results from the upstream site indicated that the sediment composition (Fig. 1) was largely composed of very fine to coarse sand (53 μm – 500 μm) and high TOC according to the USEPA (1991) classification system
Summary
Metals (e.g. V, Cd, Pb and N) and nutrients (P, N and NH4+) can enter the aquatic environment (Dallas and Day, 2004) through naturally occurring events as well as anthropogenic activities. Both pollutants and contaminants can accumulate in the sediment and may be re-released into the overlying water through chemical, physical and biological processes. The Phytotoxkit test is conducted using three plant species (Lepidium sativum, Sinapis alba and Sorghum saccharatum). This test kit has been used by Czerniawska-Kusza et al (2006) to evaluate the toxicity of
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